Color is a visual attribute resulting from a psychological and physiological response to light waves of a specific frequency impinging upon the eye. The perception of color results from the combined output of three sets of retinal cones having peak sensitivities in the red, green and blue portions of the electromagnetic spectrum. Different levels of stimulus to each set of retinal cones gives rise to the ability to perceive a large range of colors.
Conventional approaches to naming and describing colors have included systems based on color encodings which represent components of a color in terms of a position or coordinates in a usually three dimensional color space. An abridged list of such color encodings includes RGB, SWOP, CYMK, XYZ and CIELAB.
There is a considerable body of research devoted to color naming. Much of this research is based on the findings of Berlin and Kay (1991), who found universal patterns in color naming, and identified the eleven basic color names of red, green, yellow, blue, brown, pink, orange, purple, white, gray and black.
Unconstrained color naming often makes use of modifiers, or secondary terms, to better specify a color. Some modifiers are color specific, and other modifiers are general color modifiers which are applicable to multiple hues. General color modifiers include, for example “light” and “dark”. Other color modifiers include, for example “lime” and “royal”.
Hierarchical color naming systems have been proposed which apply a modifier to a color name. However, these are often based on assumptions about the use of the modifiers. For example, a given modifier may be assumed to have a clear delineation of boundaries which define the scope of the modifier in a given hue plane.
In the ISCC-NBS system, a hierarchy of modifiers is used to describe a given color. This system uses a fixed sequence of lightness and chroma modifiers for a given hue angle to partition a range of color. Using the ISCC-NBS color naming hierarchy, one color name modifier is mapped to a specific region in the color space. Two modifiers may be included in some regions of the space.
However, the model is limited in its flexibility and does not accommodate a comprehensive range of modifiers. Revisions have been proposed but these have focused primarily on the selection of modifiers, or the boundaries defining the modifier region in the color space.
It would be desirable to provide a system for incorporating color naming modifiers which is flexible, and reflects actual patterns of natural language usage.